Ink jet recording systems in which water-based ink is ejected through a nozzle having fine pores to form an image on the surface of an ink-jet recording material are widely used in photography or printing, due to their low noise during recording, ease of forming full-color images, possibility of performing rapid recording, lower cost than other printing devices, and so forth.
In recent years, an image with a quality equivalent to that of silver-halide photography or that of process printing has been realized, because of enhanced detail and speedup of a printer. However, the quality of recorded images significantly varies depending on the recording materials used. The recording materials are significantly differentiated in accordance with the intended purpose thereof, such as, for example, photographic application, printing application, general office application, or the like.
In order to realize high-image quality and high-image preservability, improvements to ink have also been made, and an ink in which a hydrophobic coloring pigment with an excellent water resistance and excellent light resistance is dispersed (hereinafter, referred to as a “pigment ink”) has been put to practical use in addition to a water-based dye ink containing a highly-hydrophilic coloring agent conventionally used mainly (hereinafter, referred to as a “dye ink”). Accordingly, a recording material that can produce a high-quality image using both dye ink and pigment ink has been in great demand. In particular, there has been a great demand for an ink-jet recording material that exhibits favorable scratch-resistance at a printed portion even if pigment ink is used, the difference between blank portion gloss and printed portion gloss of the ink-jet recording material being small when printing is performed using the pigment ink, the ink-jet recording material being suitable for a photographic application, printing application, or the like.
In order to realize image recording density, smoothness, and ink absorbing capability, various proposals have been made.
In order to realize ink absorbing capability, there is disclosed a case in which at least one layer is formed so that one peak of the hole distribution curve of the uppermost layer is positioned at a location of between 0.2 μm and 10 μm and at least two peaks of the hole distribution curve of all the ink-receiving layers are positioned at a location of between 0.2 μm and 10 μm and at a location of 0.05 μm or less, respectively (see, for example, Patent Document 1). Although the ink-absorbing rate is significantly enhanced, it is required that the ink-receiving layer mainly contain a pigment with a particle diameter of 1 μm or more so as to obtain such an ink-jet recording material. If a recording layer mainly contains the pigment with a particle diameter of 1 μm or more, not only gloss thereof but also image density are low, and round dots are not realized, and thereby image uniformity is extremely low.
In order to realize gloss, print density, ink absorbing capability, dot-roundness, an attempt has been made to use at least two kinds of fine pigment (each having a particle diameter of 1 μm or less) to form a recording layer (see, for example, Patent Documents 2 and 3). If the fine pigments with a particle diameter of 1 μm or less are used, sufficient print quality is realized with a dye ink. However, in the case where printing is performed with a pigment ink, scratch-resistance of the pigment ink is insufficiently realized, and the difference between blank portion gloss and printed portion gloss is significant, and therefore utilization for photographic application, particularly printing application in which printing is often performed with a pigment ink is difficult.
An attempt has been made to formulate a matting agent with a specific diameter of 1 to 10 μm and a colored pigment with a particle diameter of 1 μm or less are formulated with a fine pigment with a particle diameter of 500 nm or less on a water-resistant support for applying the resultant to perform proof-printing (see, for example, Patent Document 4). However, since one recording layer basically serves to receive ink, the separation rate of a solvent in ink is slow, the scratch-resistance of pigment ink is not sufficient, color tone is not stable, and print density is not sufficiently exhibited.    Patent Document 1: Japanese Patent Application, First Publication No. S 58-110287.    Patent Document 2: Japanese Laid-Open Patent Application, No. 2004-174810.    Patent Document 3: Japanese Laid-Open Patent Application, No. 2003-211825.    Patent Document 4: Japanese Laid-Open Patent Application, No. 2004-001449.